1. Field of the Invention
The present invention relates to a process for producing an epoxy resin auxiliary in the form of liquid reclaimed from rigid polyurethane foam. The present invention also relates to an epoxy adhesive produced from this reclaimed liquid.
2. Description of the Prior Art
Rigid polyurethane foam is widely used in large quantities in a variety of industrial fields (such as shipping, aircraft, vehicles, plants, heat insulators, construction and building, furniture, and interior) on account of its lightness, heat insulating properties, and good processability. The production and fabricating of the Rigid polyurethane foam to be used are performed by slabstock foaming method, pour-in-place method, spraying method, or panel-molding method etc. The production, fabrication, and use of rigid polyurethane foam are accompanied by a large amount of scrap (waste) foam. There is no effective reclaim method of the scrap foam, and the amount increases in recent years. Therefore it is of urgent necessity to develop a method for effectively reclaiming ever increasing scrap foam.
Much has been proposed about the technique of reclaiming rigid polyurethane foam scrap. For example, it is known to react foam scrap with glycol to recover polyol as a raw material. Further it is known to crush foam scrap to be used as filler, or to be used as reactive filler after treatment (to impart reactivity) with an amine in polyether polyol (Japanese Patent Publication No. 3689/1991).
The first reclaiming method mentioned above involves complex steps of foam decomposition, addition of epoxide, and purification. It gives rise to a colored liquid in low yields and the reclaim efficiency is very low because all except polyol is discarded.
Crushing (the second method) merely gives rise to a filler which degrades the resulting composite material due to the lack of reactive groups. The reactive filler obtained by the third method can prevent from a fall in product-properties, but is limited in its addition ratio, and another useful use of this filler is not referred.
So far, nothing has been known about how to utilize a liquid reclaimed from rigid polyurethane foam as an adhesive without further processing.